Boards with no bottom resist?

[Faringdon]

Hi,
I just sent  off gerbers for a 4 layer SMPS PCB to PCB train in Ireland.  Components are only on one side....all is through hole....daughter boards hold the SMD.
I forgot to send off the "bresist" layer in the gerbers.
I also forgot to add the component designators to the topsilk layer.
...So do you think they will put solder resist over all the bottom side pads and make it unsolderable?

[IconicPCB]

Of course You can and should.

The sooner the better as it minimises the effort the factory puts into the half arsed task.
The solder mask is among the final additive stages of production and there shouldn't be too much cost associated with the early engineering work changes brought on by addition of new data layer,

[jpanhalt]

If you are using Eagle, through hole pads should protect the bottom (solderable) layer from getting resist over those pads.  Frankly, I have never done that (sent without proper bottom layers).  Check what layers show on the bottom layers.  However communication with your boardmaker should take precedence over worrying about it here.